A nice article about how to use Shion, a little scripting, and a couple of INSTEON modules to efficiently cool an upstairs office is available at PommePause, the website of Guillaume Boudreau .

I love this kind of information because it demonstrates that you don't need a lot of equipment or technique to solve a common, yet vexing, problem. For another approach to this type of problem, see A Smarter, But Not the Smartest, Thermostat.